Ideal Gas Volume Calculator

Calculating Gas Volume With the Ideal Gas Law

When pressure, temperature, and amount of gas are known, volume follows directly from the ideal gas law. Chemists use this to plan reaction vessels, and engineers size expansion chambers or estimate how much space a stored gas will need.

Volume Formula

From $PV = nRT$:

$$V = \frac{nRT}{P}$$

With $n$ in moles, $T$ in kelvin, $P$ in pascals, and $R = 8.314\ \text{J mol}^{-1}\text{K}^{-1}$, volume comes out in cubic meters. Multiply by 1000 for liters.

Molar Volume at STP

One mole at 273.15 K and 101,325 Pa occupies about 22.414 L. That molar volume changes with temperature and pressure, which is why all three variables matter.

Frequently Asked Questions

Why does higher pressure reduce volume?

At fixed moles and temperature, squeezing a gas increases pressure and decreases volume. The inverse relationship follows directly from V = nRT/P.

Can I use atm for pressure?

Yes. Choose atm in the unit selector. The tool converts to pascals before calculating volume.

What is molar volume?

Molar volume is the volume occupied by one mole of gas. For an ideal gas it equals RT/P and depends on temperature and pressure.

Why show both liters and cubic meters?

Liters are common in chemistry labs while cubic meters are SI. Both are displayed so you can use whichever fits your workflow.

Does doubling moles double volume?

At constant pressure and temperature, yes. Volume is directly proportional to the amount of substance in the ideal gas model.

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Ideal Gas Volume Calculator

Calculating Gas Volume With the Ideal Gas Law

Volume Formula

Molar Volume at STP

Frequently Asked Questions

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